The present invention relates to a tape cassette for a tape recorder (hereinafter referred to as VTR) and more particularly to a lid locking device of the tape cassette. The tape cassette is inserted into the VTR, wherein a tape is exposed for the tape cassette by opening the lid located at the front of the tape cassette. A drumhead of the VTR can contact the tape for reproducing audio and video signals recorded on the tape or for recording audio and video signals to the tape. When the tape cassette is ejected from the VTR, the tape is protected in the cassette by closing the lid.